Controlling Mechanical Processes in a Modern House (Smart ... · All Arduino boards can be...

مجلة الجامعة األسمرية للعلوم األساسية والتطبيقية

2112 ، ديسمبر(2، العدد )( 1) السنة

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Controlling Mechanical Processes in a Modern House (Smart House)

Abdusalam I. Al-khwaji

1, Abdusalam M. Sharf

2, Abdallah O. Hawal

3, Saleh N. Ben

Najim4

1 AL Asmarya Islamic University Mechanical Engineering Department, College of Engineering, [email protected] 2 Mechanical Eng. Department, Elmergib University, Alkhoms, Libya. [email protected]

3 Electrical Eng. Department, Elmergib University, Alkhoms, Libya. [email protected] 4 AL Asmarya Islamic University Mechanical Engineering Department, College of Engineering, [email protected]

ABSTRACT

Comfort, Security and safety are very important factors to consider during design of a modern

house. In fact, automated houses (smart houses) have great impact in maintaining healthy lifestyle

and minimize energy usages. Maintaining all house processes in preciseness, accurately, and

repeatedly manner are very crucial to achieve our goal. Human comforts and safety require

monitoring each sub-dynamic system that is in a daily routine and during 24-hours. As an example of

common domestic controlled processes are watering garden, opening/closing doors, lighting, fire-

alarms, safety-alarms, and air-condition. Without automation these processes that will require a

responsible person to accomplish each task in a reputable schedule- time. The fact is that rarely one

has time to do all of his/her house work or maybe another case where a disable resident needs help

to maintain these mentioned processes.

This research paper covers an available and easy way for everyone to automate his/her house

using an affordable technique which makes use of small microcontroller called Arduino. The

development of smart house, which can automatically open/close doors, watering garden, maintain

security (alarm from dangerous), lighting during dark-time, controlling air-condition and display the

results in an LCD screen. Feedback signals from each of the mentioned five close-loop control system

are collected by the corresponding sensing methods. Soil-wetness, Ultrasonic-distance, Photocells,

electronic thermometer are used as feedback measurement instruments, which were used to control

each of the home-process. All the controlling processes and steps were coded and uploaded to

Arduino- UNO.

Keywords: smart house; soil-wetness sensor; temperature control; Arduino; ultrasonic sensor

mailto:[email protected]






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1. INTRODUCTION

The process of maintaining complete control of a dynamic system requires feedback (signal

from a sensors) to direct the system toward doing its required functions. In this paper, the dynamic

system under study is going to be five dynamic processes. A feedback signals are collected from

ultrasonic, photocells, soil-wetness, and electronic thermometer sensors. Then the system will try to

maintain five design parameters by comparing feedback signals versus the specified operation

points. One of the feedback carriers of the five close-loop control system was the piezoelectric

ultrasonic transducer (HC-SR04). The project was zoomed down to a level of 1 m: 1 cm scale, to allow

us to visualize the system, but we still can have the same result, when we built the system in actual

scale. The automated house model is expected to smooth the controlling process and make it easier

to reduce the efforts required to maintain the controlling process during 24 hours.

In this project, an Arduino- microcontroller was used to control all needed activities. Arduino

microcontroller has been used in controlling many mechanical and medical devices. Arduino has

been used to control automatic parking lots [1], gas valve [2], pulse signal detection [3], heart rate

monitoring [4], and other controlling projects.

This project is designed to demonstrate an optimal way to automate a house and to reduce the

energy consumption required to run the house’s activities. The goal of the present research is to

evaluate mechanism of the automated smart house system. The system control, measurements, and

instruments are all tested during operation and a report of their preciseness, sensitivity, and

repeatability was documented in this paper.

2. ARDUINO MICROCONTROLLER The Arduino is name of a company which produces open-source small (microcontroller

boards) hardware and Software. Arduino applications can be seen in many fields, such as; industrial

controllers to control many industrial production processes, or as part of an instrument to measure

specific physical quantity (Temperature, Pressure, etc.). These systems (controller) consist of sensors

which transfer feedback signal (digital- or analog-signals) to an Arduino-board. Arduino boards are

primarily programmed using the C and C++ programming languages [7]. The only limitation of an

Arduino boards is that the sensed voltage range is designed to be between 0 and +5 V which will

require extra work in case a feedback-sensed voltage was negative.



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Programming

All Arduino boards can be programmed with the (Arduino Software (IDE)) using C and C++

programming languages [8-9].

Arduino Uno Hardware

Arduino Uno is a microcontroller board based on the ATmega328P. It has 14 digital

input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz quartz crystal,

a USB connection, a power jack, an ICSP header and a reset button. It contains everything needed to

support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-

to-DC adapter or battery to get started [9]. In this project, sensors-structure was built for each sensing

method. As an example, for HC-SR04 sensors, to get an optimal way to transfer input/output data

from/to Arduino-pins , we introduce the structure as:

Structure Transducer

{ Integer Trigger Pin;

Integer echo Pin;

Float Distance; };

3. DISTANCE MEASUREMENT WITH ULTRASONIC

TECHNIQUES

Ultrasonic measurement instrument is compound of a transmitter (transmits an ultrasound wave)

and a receiver (receives the wave). As an example of an ultrasonic transducer is the model of HC-

RS04 ultrasonic transducer. Each HC-SR04 module has an ultrasonic transmitter, a receiver and a

control circuit. The four transducer’s pins are VCC (Power), Trig (Trigger), Echo (Receive), and GND

(Ground). The basic principles of an ultrasonic transducer are to measure the time between

transmission of an ultrasonic energy from transmitter and receipt of that energy by a receiver. Then,

the distance d can be calculated from the following equation [6]:

(1)

where v is ultrasound velocity and t is the time consumed for the signal to travel between transmitter

and receiver of the sensor. An important systematic error associated with this instrument is the

variability of the ultrasound velocity with environment temperature according to equation (1).



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Timing diagram

The distance through the time interval between sending trig-signal and receiving echo-signal can

be calculated from the following Formula: μS / 58 = centimeters; or: the range = maximum time *

velocity (340 m/sec at 20 Co) / 2; It is recommended to use 60ms measurement cycle [1].

( )

( )

(2)

3.1. CHARACTERIZING ULTERASONIC SENSOR

The ultrasonic wave speed changes depending in the medium through which the wave travels.

Transmission speeds in common media are given in Table 1. When the media is air, the speed of

ultrasound is affected by environmental factors such as temperature, humidity and air turbulence. Of

these, temperature has the largest effect. The velocity of sound through air varies with temperature

according to:

( ) (3)

where T is the temperature in °C. Thus, even for a relatively small temperature change of 20 degrees

from 0°C to 20°C, the velocity changes from 331.6m/s to 343.6m/s.

Humidity changes have negligible effect. When the relative humidity increases by 20%, the

corresponding increase in the sound velocity is 0.07% (corresponding to an increase from 331.6m/s to

331.8m/s at 0°C). Changes in air pressure itself have also negligible effect on the velocity. Similarly,

air turbulence normally has no effect (though note that air turbulence may deflect waves away from

their traveling direction). However, if turbulence involves currents of air at different temperatures,

then random changes in ultrasound velocity occur according to equation (3). Wind also can alter the

traveling direction of the waves. For an air flow with speed of 10 km/h, the deflection of the traveling

wave can be by 8mm over a distance of 1m.

Table 1 Speed of sound through different environments

Medium Velocity (m/s)

Air 331.6

Water 1440

Wood (pine) 3320



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Calibrating HC-SR04, TMP36, and Soil Moisture Transducers

Experimental measurements were obtained using a HCSR04 Ultrasonic transducer to

recalibrate and test the instrument at 20 C0 and for different known measurement inputs of {0, 5, 10,

15, 20 25, and 30 centimeters} as in figure 1-a. After that another sets of known measurement inputs

of {0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 meters} are collected as illustrated in figure 1-

b. Relation between measurement inputs and instrument outputs can be seen as a linear for the

range between 3 cm and 5 meters. The sensitivity is K = μS / 58 centimeters [1].

Figure 1 Calibration of the HC-SR04 for input range (a) between 0 & 30 cm at 20 C

o (b) Between 0 & 5 meters at 20 C

o

Analyzing sensitivity drift Caused by ambient temperatures change

To analyze and quantify how much drift there is for each change in medium’s temperatures, as

indicated in section 3.1 equation 3. The speed of sound in air at each temperatures of {0, 20, 60, 80,

and 100 Co} was calculated from equation 3, and each calculated speed of sound at each temperature,

was used to measure range of known measurement inputs. The corresponding instrument outputs can

be seen in y-axis, and the known measurement inputs are clarified in the x-axis of figures (2-a) and (2-

b) [1].



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Figure 2 Sensitivity drift of HC-SR04 transducer to different ambient temperatures (Measurement instrument outputs versus

known inputs between (a) 0 & 30 cm, (b) 0 & 5 meters

The calibration process of the soil-moisture transducer was made by reading an analog signal from

Arduino-analog pin A0 for four simulated signal inputs which are generated by introducing the soil-

moisture transducer to four simulated soil conditions. The first condition represents a case of 0%

water (dry soil). While the second simulates a case of %100 water (Soil saturated with water), and

then come the rest of two cases which are %20 and %50 water in the soil. The signal output was

about 5 volts for dry soil, 0.5 volts for %100 water (soil saturated with water represents uneconomic

case). From the curve in figure 3, we can see that an economic choice is going to be the case of soil

with %20 water which provides output of 4 volts. This optimal signal output is going to be used as the

feedback control signal to run the pump. Above 820 units (4 volts), the pump is going to be called to

run. It has been stated in TMP36-datasheet that the calibration factor is10 mV/°C, and the accuracy is

±2°C. The operating range is from −40°C until +125°C [7]. When you calibrate a TMP36 sensor, you

will notice that 3.3v reference has precise results among the 5v and less noise. To convert the

number from 0 until 1023 from Analog Digital Converter to 5v, we use the following formula: Vout

(mV) = (reading from ADC) *(1000mV/V) * (from 0 until 5 V) / (1024). If the used voltage reference

was 3.3v: Vout (mV) = (reading from ADC) * (1000 mV/V)* (from 0 until 3.3 V) / (1024). The

temperature output value can be obtained as: T (Co) = [Vout (mV) – 500] / 10.



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Figure 3 Calibration a soil moisture transducer

3.2. MODELING THE AUTOMATED SMART HOUSE

Figure 4 illustrates components which were used to build the simulated automated smart

house. The system consists of an I2C serial LCD 1602 module, one HC-SR04 Ultrasonic

transducers, one Parallax servo, one photo-resistor, one electronic thermometer TMP36 and

two Arduino boards (Uno and Mega). Figures 5 & 6 illustrate the final sitting of the control

system drawing with Fritzing-software. The number of sensors was used here, are only for

simulation proposes, that means for using this system in controlling real house scale, the

number will be proportional to the house’s size.

I2C Serial LCD 1602

Module

HC-SR04 Ultrasonic transducer



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Parallax Servo

Arduino Uno

Soil Moisture Sensor

Figure 4 system components

Figure 5 design of the simulated parking gate



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Figure 6 design of the simulated parking gate

4. SYSTEM CONTROL USING ARDUINO A close control system was built as illustrated in figure 7 & 8. The HC-SR04 Ultrasonic, photo-

resistor, TMP36 and SEN13322 transducers provide necessarily feedback signals to adjust entry/exit

gates depending on our design control parameters, which are the availability of water in the soil,

appearance of a person in front door, lightness or darkness of outdoor, etc. As an example of these

control processes, is that the door will not open if the available space was less than {Measured

Distance >= 10 cm}. A resident must stand in a distance less than or equal to 10 cm from the door, in

order to send feedback signal to the servo-motor to open the door. Figure 8 illustrates one of usage

of Serial Plotter, which describes simulation of opening/closing a door. The gates rotate 90 degree to

allow a resident to enter to, or exit from, the door. The unit-pulse signal is illustrated in figure 8



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describes the feedback at which the door’s servo starts to rotate from zero-degree to 90 degree

(opening position), in order to allow a resident to enter the house.

Figure 7 Close loop control system

Figure 8 Arduino Serial Plotter Simulation of a door control system using feedback from HC-

SR04 transducers (Blue-curve represents entering while red is for closing the door)

5. RESULTS The house automation using Arduino, appear clearly to have precise and accurate functionality,

where series of accurate transducers were used. The arrangement was designed and positioned

carefully to avoid any disturbance from another objects during each control process. The accuracy of



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HC-SR04 transducers in detecting obstacles (residents) was tested during experimental characteristic,

where the transducer was calibrated to test the measurement range. The measurement range was

from 3 cm until 5 m. The effect of changing environmental condition (Ambient temperature) was

carefully tested, and confirmed that the optimal environmental temperature was 20 Co and also

there will be some error corresponding to the change of the ambient temperatures, since speed of

sound varies when ambient temperature was changed. Moreover, a carefully calibration of the SEN-

13322 sensors are carried out and the results show good repeatability and perfect accuracy.

6. CONCLUSIONS In this paper we presented detailed design process of the simulated automated smart home

using Arduino. The sensors which were used to provide the necessary feedback signals are SEN-

13322 (Soil moisture sensor), Photo resistors (Light sensor), TMP36 (Temperature sensor), and HC-

SR04 (Distance sensor). Detailed investigation of the static characteristic of the HC-SR04 and SEN-

13322 sensors were performed to estimate sensitivity, and minimum/maximum detecting range. This

work provides validation of repeatability, stability and accuracy of the automated smart home

system. The process of opening/closing doors, turning the watering-pump on/off, controlling air-

condition, and lighting the garden’s lamps were tested. The reliability, accuracy, precision and

reproducibility of all used sensors were tested using wide range of known measurement inputs

(known distances, temperatures, and soil moisture conditions) at ambient temperature of 20 Co.

we’ve documented maximum/minimum measurement range for the HC-SR04 sensor(from 3cm until

5m) as in figure 1, and for the SEN-13322 sensor as indicated in figure 3. Then we have investigated

the effect of changing the environmental condition (ambient temperatures) in the instrument

outputs. The results of ambient temperature affect were documented in figure 2, where distance

measurements were made at different ambient temperatures. The effect of changing the

environmental condition on the efficiency of the SEN-13322 sensor is negligible. The only

environmental condition could affect the HC-SR04-transducer measurements was ambient

temperatures but for usual temperature range there will be no effect during the system operational

time. This research is in the first stage, and is designed to catch attention of new undergraduate

researchers to participate in the mechanical Engineering Department research group in the area of

dynamic systems and control.



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